I've been waiting for several weeks for a very large BoB trade ... I just checked my BoB page and there's a message at the bottom "Other boxer is no longer a member." Does that mean her BoB subscription ran out? I'm hoping that's all that happened and my books are still on the way ...

I guess it's possible their box-o-books membership expired, but I'd check the person's bookshelf.  It's possible they had several delinquent deals and had their account suspended for it.  If their bookshelf is gone and replaced with a message about no longer having an active account then I'd bet that's what happened.  If that's the case, on one hand you probably won't get your books, but on the other hand for them to get their account back requires either sending you your books or enough credits to make up for the books you sent. 

I just had the same thing happen to me. I lost 2 books this time even though I checked their feedback before I swapped. I've been a boxer for 3 years and this has only happened twice but it's still annoying.